Precautions

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to use it. Blood tests may be needed to check for unwanted effects.

You should not use tolvaptan together with clarithromycin (Biaxin®), indinavir (Crixivan®), itraconazole (Sporanox®), ketoconazole (Nizoral®), nefazodone (Serzone®), nelfinavir (Viracept®), ritonavir (Norvir®), saquinavir (Fortovase®, Invirase®), or telithromycin (Ketek®). Using these medicines together may increase risk for more serious side effects.

Check with your doctor right away if you have drowsiness, confusion, mood changes, muscle weakness in the arms or legs, seizures (convulsions), or trouble with speaking, swallowing, or controlling body movements. These may be symptoms of a serious and rare condition called osmotic demyelination syndrome (ODS). This may occur if the sodium blood level rises too fast.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Certain medicines or illnesses, such as vomiting or diarrhea, may cause you to lose too much body water (dehydration). If you think you are dehydrated, tell your doctor right away. Always have water available to drink if you are thirsty, unless your doctor tells you otherwise.

Ask your doctor first before you use any medicine or salt substitutes that contain potassium.

You should not eat grapefruit or drink grapefruit juice while you are taking this medicine. Grapefruit or grapefruit juice may increase the effects of tolvaptan in your body.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.